Symposium: Papers Presented at the 2011 Meeting of the International Hip Society 28 articles
Although numerous in vitro studies report on the tribological performance of and, separately, on the corrosion properties of cobalt-based alloys in metal-on-metal (MoM) bearings, the few studies that take into account the synergistic interaction of wear and corrosion (tribocorrosion) have used canonical tribo-test methods. We therefore developed synergistic study using a test method that more closely simulates hip bearing conditions.
Stabilization of a pelvic discontinuity with a posterior column plate with or without an associated acetabular cage sometimes results in persistent micromotion across the discontinuity with late fatigue failure and component loosening. Acetabular distraction offers an alternative technique for reconstruction in cases of severe bone loss with an associated pelvic discontinuity.
Corrosion at the Cone/Taper Interface Leads to Failure of Large-diameter Metal-on-metal Total Hip Arthroplasties
Metal-on-metal (MoM) THAs have reduced wear rates compared with metal-on-polyethylene. However, elevated serum metal ion levels and pseudotumors have been reported in large MoM articulations.
Up to 2% of THAs are complicated by infection, leading to dissatisfied patients with poor function and major social and economic consequences. The challenges are control of infection, restoration of full function, and prevention of recurrence. Irrigation and débridement with or without exchange of modular components remains an attractive alternative to two-stage reimplantation in acutely infected THAs but with variable results from previous studies.
Do Revised Hip Resurfacing Arthroplasties Lead to Outcomes Comparable to Those of Primary and Revised Total Hip Arthroplasties?
A theoretical clinical advantage of hip resurfacing (HR) is the preservation of femoral bone. HR femoral component revision reportedly yields postoperative function comparable to that of primary THA. However, few studies have looked at the outcome of both HR femoral and acetabular side revisions.
Proximal femoral nail antirotation devices (PFNAs) are considered biomechanically superior to dynamic hip screws for treating unstable peritrochanteric fractures and reportedly have a lower complication rate. The PFNA II was introduced to eliminate lateral cortex impingement encountered with the PFNA. However, it is unclear whether the new design in fact avoids lateral cortex impingement without compromising stability of fixation and fracture healing.
Surgical Technique: The Capsular Arthroplasty: A Useful But Abandoned Procedure for Young Patients With Developmental Dysplasia of the Hip
Codivilla in 1901, Hey Groves in 1926, and Colonna in 1932 described similar capsular arthroplasties—wrapping the capsule around the femoral head and reducing into the true acetabulum—to treat completely dislocated hips in children with dysplastic hips. However, these procedures were associated with relatively high rates of necrosis, joint stiffness, and subsequent revision procedures, and with the introduction of THA, the procedure vanished despite some hips with high functional scores over periods of up to 20 years. Dislocated or subluxated hips nonetheless continue to be seen in adolescents and young adults, and survival curves of THA decrease faster for young patients than for patients older than 60 years. Therefore, joint preservation with capsular arthroplasty may be preferable if function can be restored and complication rates reduced.
The relative risk of revision of the Titanfemoral stem due to aseptic loosening increased after 2000; however, the reasons for this have not been established. A retrieval analysis was initiated with the aim of delineating the failure mechanism.
Reconstruction rings and bone allografts have been proposed to manage severe acetabular bone loss. However, a high early failure rate of the Graft Augmentation Prosthesis (GAP) II reinforcement ring (Stryker Orthopaedics, Mahwah, NJ, USA) has been reported in one small series.
Highly Crosslinked Polyethylene Does Not Reduce Aseptic Loosening in Cemented THA 10-year Findings of a Randomized Study
Polyethylene (PE) wear particles are believed to cause aseptic loosening and thereby impair function in hip arthroplasty. Highly crosslinked polyethylene (XLPE) has low short- and medium-term wear rates. However, the long-term wear characteristics are unknown and it is unclear whether reduced wear particle burden improves function and survival of cemented hip arthroplasty.
Head Material Influences Survival of a Cemented Total Hip Prosthesis in the Norwegian Arthroplasty Register
High prosthesis survival is reported for total hip prostheses with metal and alumina heads, but direct comparisons of a single prosthesis design with one of two different head materials has seldom been studied. Prostheses with zirconia heads are less commonly used than metal and alumina heads, and the few reports suggest variable results with zirconia heads.
Dislocation after THA continues to be relatively common. Dual mobility sockets have been associated with low dislocation rates, but it remains unclear whether their use in primary THA would not introduce additional complications.
Avoiding complications after hip arthroplasty with hard-on-hard bearings, especially metal-on-metal, correlates with the position of the acetabular component. Supine imaging with conventional radiography has traditionally been utilized to assess component inclination (abduction), as well as anteversion, after THA and surface replacement arthroplasty (SRA). However, most adverse events with hard bearings (excessive wear and squeaking) have occurred with loading. Standing imaging, therefore, should provide more appropriate measurements.
The goal of periacetabular osteotomy (PAO) is to delay or prevent osteoarthritic development in dysplastic hips. However, it is unclear whether the surgical goals are achieved and if so in which patients. This information is essential to select appropriate patients for a durable PAO that achieves its goals.
Tantalum Acetabular Cups Provide Secure Fixation in THA after Pelvic Irradiation at Minimum 5-year Followup
Pelvic radiation has been commonly used to treat gastrointestinal, genitourinary, or hematopoietic malignancies. Conventional THA in these patients reportedly have high rates of fixation failure. Although secure short-term fixation reportedly occurs with trabecular metal implants following pelvic radiation, it is unclear whether the fixation is durable.
Uncemented press-fit cups provide bone fixation in primary THA, but the use of screws is sometimes necessary to achieve primary stability of the socket. However, it is unclear whether and when screws should be used.
Cementing Acetabular Liners Into Secure Cementless Shells for Polyethylene Wear Provides Durable Mid-term Fixation
In a previous experiment studying cementation of liners into cementless acetabular shells, placing grooves in the liner in a spider-web configuration created the greatest construct strength. Scoring shells without screw holes or other texturing helped prevent failure at the shell-cement interface. However, it was unclear whether these practices caused durable constructs in patients.
Although navigated THA provides improved precision in implant positioning and alignment, it is unclear whether these translate into long-term implant survival.
Residual Perthes and Perthes-like hip deformities are complex and may encompass proximal femoral deformity, secondary acetabular dysplasia, and associated intraarticular abnormalities. These intraarticular abnormalities have not been well characterized but may influence surgical technique and treatment outcomes.
Alumina Heads Minimize Wear and Femoral Osteolysis Progression After Isolated Simple Acetabular Revision
Patients with THA requiring cup revision for acetabular osteolysis may have a stable stem component without loosening. However, it is unclear whether isolated cup revision halts femoral osteolysis progression.
Return to sport is a key patient demand after hip arthroplasty and some patients are even involved in high-impact sports. Although polyethylene wear is related to the number of cycles and the importance of the load, it is unclear whether high-impact sport per se influences THA durability.
Modern metal-on-metal hip resurfacing arthroplasty designs have been used for over a decade. Risk factors for short-term failure include small component size, large femoral head defects, low body mass index, older age, high level of sporting activity, and component design, and it is established there is a surgeon learning curve. Owing to failures with early surgical techniques, we developed a second-generation technique to address those failures. However, it is unclear whether the techniques affected the long-term risk factors.
Socket fixation in patients with acetabular dysplasia can be technically demanding but the use of structural grafts can help to reconstruct the original center of hip rotation. Because reported survival rates differ, construct survival seems to depend on the technique of graft preparation and fixation.
Edge wear is an adverse factor that can negatively impact certain THAs. In some metal-on-metal THAs, it can lead to adverse tissue reactions including aseptic lymphocytic vasculitis-associated lesions and even to pseudotumor formation. In some ceramic-on-ceramic THAs, it can lead to squeaking and/or stripe wear. Edge wear in metal-on-metal and ceramic-on-ceramic THAs can also be associated with accelerated wear across the articulation of these joints.
Do Survival Rate and Serum Ion Concentrations 10 Years After Metal-on-Metal Hip Resurfacing Provide Evidence for Continued Use?
Owing to concerns attributable to problems associated with metal-on-metal bearing surfaces, current evidence for the use of hip resurfacing is unclear. Survival rates reported from registries and individual studies are controversial and the limited long-term studies do not conclusively allow one to judge whether hip resurfacing is still a reasonable alternative to conventional THA.
Techniques that ensure femoral bone preservation after primary THA are important in younger patients who are likely to undergo revision surgery.
Despite advances in primary THA, dislocation remains a common complication. In New Zealand (NZ), dislocations are reported to the National Joint Registry (NJR) only when prosthetic components are revised in the treatment of a dislocation. Closed reductions of dislocated hips are not recorded by the NJR.